Micro current grounding waveform amplification circuit
By designing a small current ground waveform amplification circuit including a current transformer, a current amplification module and a current scaling module, the problem of insufficient sampling accuracy of the micro current in the prior art is solved, and the precise amplification and adjustment of the micro current signal is achieved, which significantly improves the sampling accuracy.
Patent Information
- Application Number
- CN202421856074.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-01
- Publication Date
- 2025-05-13
- Estimated Expiration
- 2034-08-01
AI Technical Summary
The prior art is not accurate enough when sampling a tiny current, especially when the sampling current is less than 200mA, ordinary sampling circuits cannot provide sufficient accuracy.
Design a small current ground waveform amplifier circuit, including a current transformer, a current amplification module and a current scaling module. Through the ratio operation of the current transformer, the amplification processing of the current amplification module, and the scaling adjustment of the current scaling module, the accurate sampling signal is finally output.
It significantly improves the precise amplification and adjustment of micro current signals and improves the accuracy of sampling.
Smart Images
Figure CN222868893U_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field related to current transformers, and in particular to a small current grounding waveform amplification circuit. Background Art
[0002] In the prior art, current transformers are used to perform ratio conversion on the secondary current in the main circuit. At present, current transformers are generally used for conversion without other processing, and the accuracy of tiny currents is not too high, or operational amplifiers are used to simply build circuits for amplification. For the current sampling of the telemetry function in the State Grid standardized DTU, it is divided into phase current and zero-sequence current. After isolation conversion on the primary switch side, the current range input to the secondary is relatively large. When the sampled current is less than 200mA, the value sampled by the ordinary sampling circuit is not accurate enough. At this time, a more accurate sampling circuit is needed to collect tiny currents less than 200mA. Utility Model Content
[0003] In order to improve the overall sampling accuracy, the present application provides a small current grounding waveform amplification circuit.
[0004] The present application provides a small current grounding waveform amplifier circuit that adopts the following technical solution:
[0005] A small current grounding waveform amplification circuit includes a current transformer, a current amplification module and a current scaling module. The secondary current is output to the primary winding of the current transformer. The output end of the secondary winding of the current transformer is electrically connected to the input end of the current amplification module. The output end of the current amplification module is electrically connected to the input end of the current scaling module. The output end of the current scaling module is used to output a sampling signal.
[0006] By adopting the above technical solution, when the secondary current is introduced into the primary winding of the current transformer, the current transformer performs a ratio operation to convert the input secondary current in proportion; then, the converted secondary current flows through the current amplification module, which is used to enhance and amplify the current signal; then, the amplified current signal enters the current scaling module, which scales the current in proportion to the set ratio; finally, the current signal after this series of processing is output in the form of a sampling signal. The above structure can effectively and accurately amplify and adjust the tiny current signal, thereby significantly improving the accuracy of sampling.
[0007] Preferably, the current amplification module includes a first op amp U1 and a resistor R1, the output end of the secondary winding of the current transformer is electrically connected to the inverting input end of the first op amp U1, and the non-inverting input end of the first op amp U1 is grounded; the two ends of the resistor R1 are electrically connected to the inverting input end of the first op amp U1 and the output end of the first op amp U1, respectively, and the output end of the first op amp U1 is set as the output end of the current amplification module.
[0008] By adopting the above technical solution, the inverting amplification of the secondary output signal of the current transformer can be achieved through the first operational amplifier U1 and the resistor R1.
[0009] Preferably, the current amplification module further includes a switching diode D1, pins 1 and 2 of the switching diode D1 are electrically connected to the inverting input terminal of the first operational amplifier U1, and pin 3 of the switching diode D1 is grounded.
[0010] By adopting the above technical solution, the switching diode D1 is provided to achieve a voltage stabilization effect.
[0011] Preferably, the current amplification module further includes a capacitor C1, one end of the capacitor C1 is electrically connected to the inverting input end of the first operational amplifier U1, and the other end of the capacitor C1 is electrically connected to the output end of the first operational amplifier U1.
[0012] By adopting the above technical solution, the capacitor C1 is provided to achieve phase compensation.
[0013] Preferably, the current scaling module includes a second op amp U2, the output end of the current amplification module is electrically connected to the non-inverting input end of the second op amp U2 through a resistor R2, and the non-inverting input end of the second op amp U2 is also grounded through a resistor R3; the inverting input end of the second op amp U2 is grounded, and the inverting input end of the second op amp U2 is also electrically connected to the output end of the second op amp U2 through a resistor R5, and the output end of the second op amp U2 is set as the output end of the current scaling unit.
[0014] By adopting the above technical solution, the resistor R2 and the resistor R3 play a voltage dividing role, thereby reducing the output voltage value of the current amplification module; and the output voltage value of the current amplification module after the reduction processing can be re-amplified through the second operational amplifier U2.
[0015] Preferably, the current scaling module further includes a capacitor C2, the output end of the current amplification module is electrically connected to one end of the capacitor C2, and the other end of the capacitor C2 is electrically connected to one end of the resistor R2 away from the second operational amplifier U2.
[0016] By adopting the above technical solution, the capacitor C2 is used to perform a low-pass filtering function, so that the output current of the current amplification module can be more stably input to the second operational amplifier U2 for processing.
[0017] Preferably, a connection point between the resistor R2 and the resistor R3 is grounded via a capacitor C3.
[0018] By adopting the above technical solution, the capacitor C3 is used to further filter the voltage input to the second operational amplifier U2.
[0019] Preferably, the output end of the second operational amplifier U2 is grounded via a resistor R6 and a capacitor C4 in sequence, and the connection point between the resistor R6 and the capacitor C4 is set as the output end of the current scaling module.
[0020] By adopting the above technical solution, the resistor R6 and the capacitor C4 are used to form an RC filtering structure, thereby improving the stability of the output signal at the output end of the current scaling module.
[0021] In summary, the present application includes at least one of the following beneficial technical effects: the secondary current after the current transformer ratio conversion is first amplified by the current amplification module, and then scaled and adjusted by the current scaling module, and finally the sampling signal is output. Through the signal processing of the above structure, the secondary current after the current transformer ratio conversion can be amplified in an appropriate proportion, so that the tiny current signal can be effectively and accurately amplified and adjusted, thereby significantly improving the accuracy of sampling. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is a principle block diagram of an embodiment of the present application;
[0023] Figure 2 is a partial circuit diagram of a current transformer according to an embodiment of the present application;
[0024] Figure 3 is a circuit diagram of a current amplification module according to an embodiment of the present application;
[0025] Figure 4 is a circuit diagram of a current scaling module according to an embodiment of the present application.
[0026] Figure numerals: 1. Current amplification module; 2. Current scaling module. DETAILED DESCRIPTION
[0027] The following is combined with Figure 1-4 This application is described in further detail.
[0028] The embodiment of the present application discloses a small current grounding waveform amplification circuit.
[0029] Reference Figure 1 A tiny current grounding waveform amplification circuit includes a current transformer, a current amplification module 1 and a current scaling module 2 which are electrically connected in sequence. When the secondary current is input to the primary winding of the current transformer, the current transformer performs a ratio processing on the secondary current. The secondary current generated by the secondary winding of the current transformer is sequentially converted and amplified by the current amplification module 1 and scaled by the current scaling module 2, and finally a sampling signal is output. The above structure can amplify the tiny current with high precision, thereby improving the sampling accuracy.
[0030] Reference Figure 2 , pins 1 and 2 of the current transformer CT1 are used to receive the secondary current input signal, pin 4 of the current transformer CT1 is used to output the secondary current signal, and pin 3 of the current transformer CT1 is grounded. When the secondary current is input, the secondary current passes through the middle hole of the current transformer CT1 via the insulated wire, and then through the transformation of the current transformer CT1, the secondary current value is converted according to the set transformation ratio, and finally the secondary current signal IO is output. The current transformer ratio selected in this embodiment is 1A / 2.5MA, that is, the primary current value of 1A corresponds to the secondary current value of 2.5MA.
[0031] Reference Figure 3 The current amplification module 1 includes a first operational amplifier U1 and a resistor R1. The secondary current signal IO is input to the inverting input terminal of the first operational amplifier U1, and the non-inverting input terminal of the first operational amplifier U1 is grounded. The two ends of the resistor R1 are electrically connected to the inverting input terminal of the first operational amplifier U1 and the output terminal of the first operational amplifier U1, respectively, and the output terminal of the first operational amplifier U1 is used to output the voltage signal IO_S, and the inverting amplification of the secondary current signal is realized through the current amplification module 1.
[0032] The current amplification module 1 also includes a switching diode D1 and a capacitor C1. Pins 1 and 2 of the switching diode D1 are electrically connected to the inverting input terminal of the first op amp U1, and pin 3 of the switching diode D1 is grounded, which plays a role in voltage stabilization, so that the secondary current signal IO can be more stably input to the inverting input terminal of the first op amp U1. One end of the capacitor C1 is electrically connected to the inverting input terminal of the first op amp U1, and the other end of the capacitor C1 is electrically connected to the output terminal of the first op amp U1. The capacitor C1 plays a role in phase compensation.
[0033] Reference Figure 4, the current scaling module 2 includes a second amplifier U2, and the voltage signal IO_S is electrically connected to the non-phase input terminal of the second amplifier U2 through capacitor C2 and resistor R2 in turn, and the non-phase input terminal of the second amplifier U2 is also grounded through resistor R3. Wherein, capacitor C2 plays a low-pass filtering role, and resistor R2 and resistor R3 play a voltage dividing role, thereby reducing the voltage value of the voltage signal IO_S. The connection point between resistor R2 and resistor R3 is grounded through capacitor C3, and capacitor C3 plays a role of filtering and voltage stabilization. The inverting input terminal of the second amplifier U2 is grounded through resistor R4, and the inverting input terminal of the second amplifier U2 is also electrically connected to the output terminal of the second amplifier U2 through resistor R5. The output terminal of the second amplifier U2 is grounded through resistor R6 and capacitor C4 in turn, and the connection point between resistor R6 and capacitor C4 is the output terminal of the current scaling module 2, and resistor R6 and capacitor C4 form an RC filtering structure, thereby improving the stability of the output signal of the output terminal of the current scaling module 2. The output end of the current scaling module 2 can output a sampling signal IOS. The second operational amplifier U2 and its peripheral components can function as a common-mode amplifier to re-amplify the scaled voltage signal IOS.
[0034] Reference Figure 4 , the present embodiment also includes a power supply VO, and the power supply voltage value of the power supply VO in the present embodiment is set to ±12V. The positive power supply terminal of the second op amp U2 is electrically connected to the positive voltage output terminal of the power supply VO, and the positive voltage output terminal of the power supply VO is grounded through a capacitor C4, and the negative power supply terminal of the second op amp U2 is electrically connected to the negative voltage output terminal of the power supply VO, and the negative voltage output terminal of the power supply VO is grounded through a capacitor C5. In addition, in the present embodiment, the first op amp U1 and the second op amp U2 are set as two op amps in an integrated multi-op amp chip, so that the power supply VO can provide operating voltage for the first op amp U1 and the second op amp U2.
[0035] The implementation principle of a tiny current grounding waveform amplification circuit in the embodiment of the present application is as follows: when the secondary current is input to the primary winding of the current transformer, the current transformer performs ratio processing on the secondary current. The secondary current on the secondary side of the current transformer is sequentially converted and amplified by the current amplification module 1, and scaled by the current scaling module 2, and finally outputs a sampling signal. The above structure can amplify the tiny current with high precision, thereby improving the sampling accuracy.
[0036] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. A small current grounding waveform amplifier circuit, characterized in that: The invention comprises a current transformer, a current amplifying module (1) and a current scaling module (2), wherein a secondary current is output to a primary winding of the current transformer, an output end of the secondary winding of the current transformer is electrically connected to an input end of the current amplifying module (1), an output end of the current amplifying module (1) is electrically connected to an input end of the current scaling module (2), and an output end of the current scaling module (2) is used to output a sampling signal.
2. A small current grounding waveform amplifier circuit according to claim 1, characterized in that: The current amplification module (1) comprises a first operational amplifier U1 and a resistor R1, the output end of the secondary winding of the current transformer is electrically connected to the inverting input end of the first operational amplifier U1, and the non-inverting input end of the first operational amplifier U1 is grounded; the two ends of the resistor R1 are electrically connected to the inverting input end of the first operational amplifier U1 and the output end of the first operational amplifier U1, respectively, and the output end of the first operational amplifier U1 is set as the output end of the current amplification module (1).
3. A small current grounding waveform amplifier circuit according to claim 2, characterized in that: The current amplification module (1) further comprises a switching diode D1, wherein pins 1 and 2 of the switching diode D1 are both electrically connected to the inverting input terminal of the first operational amplifier U1, and pin 3 of the switching diode D1 is grounded.
4. A small current grounding waveform amplifier circuit according to claim 2 or 3, characterized in that: The current amplification module (1) further comprises a capacitor C1, one end of the capacitor C1 being electrically connected to the inverting input end of the first operational amplifier U1, and the other end of the capacitor C1 being electrically connected to the output end of the first operational amplifier U1.
5. The small current grounding waveform amplifier circuit according to claim 1, characterized in that: The current scaling module (2) comprises a second operational amplifier U2, the output end of the current amplification module (1) is electrically connected to the non-inverting input end of the second operational amplifier U2 via a resistor R2, and the non-inverting input end of the second operational amplifier U2 is also grounded via a resistor R3; the inverting input end of the second operational amplifier U2 is grounded, and the inverting input end of the second operational amplifier U2 is also electrically connected to the output end of the second operational amplifier U2 via a resistor R5, and the output end of the second operational amplifier U2 is set as the output end of the current scaling unit.
6. A small current grounding waveform amplifying circuit according to claim 5, characterized in that: The current scaling module (2) further comprises a capacitor C2, the output end of the current amplification module (1) is electrically connected to one end of the capacitor C2, and the other end of the capacitor C2 is electrically connected to an end of the resistor R2 away from the second operational amplifier U2.
7. A small current grounding waveform amplifying circuit according to claim 5 or 6, characterized in that: A connection point between the resistor R2 and the resistor R3 is grounded via a capacitor C3.
8. The small current grounding waveform amplifying circuit according to claim 5, characterized in that: The output end of the second operational amplifier U2 is connected to the ground via the resistor R6 and the capacitor C4 in sequence, and the connection point between the resistor R6 and the capacitor C4 is set as the output end of the current scaling module (2).